Train Wreck - S1-E20
Continuity mistake: When Julie goes to get her jacket, Doug's board swaps hands instantly. (00:03:40)
Continuity mistake: At the end, the shawl around Carrie's shoulder is either covering her shoulder or not depending on the shot. (00:20:50)
Continuity mistake: When Carrie is taking the shopping out of the bag, the items are constantly moving on the side without being touched. (00:03:30)
Answer: Sara hasn't been mentioned in later episodes, and it suggested in later episodes that she never existed, and that Carrie is an only child. Kevin James stated that the producers couldn't think of an good plots to use with Sara, so they left her out.